1. Field of the Invention
The present invention relates to pipe-and-ball truss arrays such as the type utilized for space trusses and space frames.
2. Description of the Prior Art
Space frames are well known in the art, such as the type normally known as pipe-and-ball space frames. Prior art space frames of this type, that is prior to the space frame described and claimed in commonly owned U.S. Pat. No. 3,882,650 by Paul F. Gugliotta, such as disclosed in British Pat. No. 1,206,399, have utilized threaded pipes which thread into the ball joints or have been of the type utilizing pipes which are welded to the ball joints. Both of these types of interconnections are costly. Some other prior art space frames, such as the structure utilized for the Polish Pavillion in the International Exhibition in Brussels in 1958, utilize tension elements, such as flexible rods, which are bolted within a hollow ball joint or sphere by nuts which are tightened to place these elements in tension, in conjunction with separate reinforced concrete members which are placed in compression. This is a costly arrangement and, furthermore, the tension elements may not be utilized where compressive loads occur nor are the concrete elements usable where tensile loads occur. Thus, such prior art pipe-and-ball truss arrays, such as employed in space frames, have not economically satisfactorily provided higher strength or resistance to compressive, tensile and axial loads without increased costs. Other prior art arrangements for use in connection with space frames are disclosed in U.S. Pat. Nos. 3,220,152; 3,632,147; and 3,789,562, as well as in French Pat. Nos. 1,073,078 and 1,489,468.
Such disadvantages of the prior art, it is believed, were overcome by the pipe-and-ball truss array described and claimed in commonly owned U.S. Pat. No. 3,882,650. However, with respect to the pipe-and-ball truss array described in that patent, there are possible disadvantages when it is desired to employ such a truss array in connection with the support of a deck surface, such as a roof deck or a wall panel, thereon. Primarily, the disadvantage flows from the fact that the pipe elements employed in such a pipe-and-ball truss array are normally not strong enough in bending to adequately support such a deck surface and, moreover, provide a relatively small area for attachment of the deck surface to the outer chords of the truss array. Although U.S. Pat. No. 3,882,650 discloses a system for attaching a skylight structure to the array by means of bolting to the hollow spheres, this arrangement is not preferred for supporting a deck surface on the array as adequate support may not be provided. Moreover, as previously mentioned, such deck surface cannot be adequately supported directly on the pipe elements forming the outer chord of such an array since such pipe elements are not sufficiently strong in bending. These disadvantages of the prior art are overcome by the present invention.